Stereotactic radiosurgery (SRS) is a common treatment modality for brain tumors and typically involves repeated doses of radiation provided to the patient over a period of time. In order to ensure that the radiation is directed to the precise target it is a common practice to make use of a positioning/fixation device to hold the patient's head in a desired, immobilized position. Since that device will be used repeatedly it is typically adjustable so that the various portions of it are in desired positions/orientations to accommodate the particular anatomy of the patient's head. Head position/fixation devices are currently available from various manufacturers. Civco Medical Solutions (hereinafter “CIVCO”) is one such manufacturer.
While the commercially available devices to hold the head of a patient immobilized, including those commercially available from CIVCO, are generally suitable for their intended purposes such devices tend to be rather complicated in structure and not ideally suited for ease of assembly and adjustment. For example, the commercially available devices from CIVCO make use of an arch or bridge member which is mounted on the couchtop (or other patient support surface) and spans the head of the patient from one side of the patient's head to the other, i.e., one leg of the arch is disposed on the left side of the patient's head, with the other leg of the arch being disposed on the right side of the patient's head. The upper portion of the arch, which bridges its two legs is arranged to mount components which are arranged to engage portions of the patient head to immobilize the patient's head. One such component is a so-called “nasion” pad, which is a silicone pad arranged to engage the nose of the patient. Another component is a bite tray which is arranged to be inserted into the patient's mouth and held between the patient's teeth. The mounting of the nasion pad and the bite tray on the arch of the CIVCO device is accomplished by means of a single long, horizontally extending arm. That long arm is arranged to be located at the upper portion of the bridge adjacent either the right side leg of the arch or the left side leg of the arch so that it extends above and parallel to the right or left side, respectively, of the patient's head. A pair of shorter transverse arm are mounted on the long arm and arranged to be positioned at various longitudinal positions therealong to accommodate particular anatomy of the patient's head. One of the transverse arms mounts the nasion pad, while the other mounts the bite tray. The nasion pad and the bite tray can be mounted on either the superior or inferior side of the transversely extending arms. Moreover, each of the transversely extending arms is arranged to be rotated about a horizontal axis so that the particular component held by it is at a desired angular orientation with respect to the underlying patient's head.
In order to provide additional space between the transverse arms and the couchtop for the patient's head, without extending the height of the arch, the CIVCO device makes use of transverse arms that are constructed so that their respective distal ends, which extend parallel to the plane of the couchtop, are offset vertically from the axes of rotation of those arms. Thus, the distal end of each transverse arm is above the axis about which the arm is rotated to provide more space below to accommodate the patient's head.
As mentioned above, and in the interest of best fitting the device to the anatomy of the particular patient, the long (longitudinally extending) arm can be positioned at one of two positions on the arch, i.e., a left side position or a right side position. Thus, for example, if the mounting of the long arm on the one side (e.g., the left side) of the arch is not desired or appropriate, and mounting on the other side (e.g., the right side) is preferred, the long arm with the transverse arms mounted thereon can be disconnected from the arch and moved to the new desired position. However, such action is a somewhat complicated procedure and risks dropping or misplacement of portions of the disassembled device.
Accordingly, a need exists for a SRS positioning/immobilization device which enables the positioning of the longitudinal (long) arm, with the transverse (short) arms mounted thereon, to be readily moved (pivoted) to either the right side of the arch or the left side of the arch without disassembling the device, and in a manner ensuring that the longitudinal arm is in the precise orientation in that desired right or left mounting position. In addition, a need exists for a device having mechanisms to adjust the position of the transverse arms at any position along the length of the longitudinal arm and lock it in place therein, while also enabling the rotation of the transverse arm about its rotational axis so that its angular orientation can be readily adjusted, set and locked in place with a single knob and without requiring removal of the transverse arms from the longitudinal arm. Further still, a need exists for a device which enables the components mounting the nasion pad and the bite tray (or any other anatomy engagement components) on their respective transverse arms to be readily disposed on either the superior or inferior side of each arm and to be readily adjusted vertically and locked in place thereat. Further yet, a need exists for a device which provides indicia indicating the appropriate position of the various components of the device, so that the device can be reused to reset the components to previously defined positions, thereby ensuring that the device can be used to immobilize the patient's head during repeated treatments. Still further yet, a need exists for a device which facilitates the mounting and securement of the device on the couchtop or a support base in a very simple, one step operation.
The subject invention addresses those needs.
All references cited and/or identified herein are specifically incorporated by reference herein.